Diane,
I worked w/ a mom w/ a similar problem.  She was BF a 2 year old w/
developmental delays.  She was getting repeated irritation & infection of her
Montgomery's glands due to her daughter's clenching during BF.

Ultimately, what worked for her was to use the dancer hand position, in which
mom supports her breast & child's jaw at the same time.  She also provided
some counter pressure on the bottom of the child's jaw when clenching
occured.  This mom felt her daughter had started to use this clenching as a
way to hold the breast.  Since using this technique, this mom finds she
begins to get irritated when she stops using the dancer hand, but has not had
any additional infections.

Ro Andersen, IBCLC
Ro NSLA @ aol.com
Winchester, MA USA